Barometric damper



Nov. 29, 1949 w. R. 'MILLER ET AL 2,489,308

BAROMETRIC DAMPER Filed Sept. 4, 1944 1N V'ENTOR.

WE. MILLER HOMER 1 JIJZIL 0N5 Patented Nov. 29, 1949 UNITED STATES OF FICE Malone, Milwaukee, Wis., assi'gnors to Perfex' Corporation,Milwaukee, Wis, a corporation of Wisconsin.

Application September 4, 1944, Serial No. 552,612

10 Claims. 1.

It has become common to provide; furnaces with barometric dampers whichmaintain constant draft in the off-take fines. These dampers usuallyconsist of a vane which. is. pivoted oilcenter and which is providedwith a biasing weight, thereby responding to thedifference" in pressurebetween. the flue and. atmosphere- As. this pressure difference ordraft. increases, the vane. moves inwardly for permitting air to enterthe flue, thereby tending to maintain. the draft constant.

It has been found that dampers. of this type: usually worksatisfactorily when. new; but grad-- ually become inoperative over along period of time. The reason for this is that the bearings becomedirty or rusty, thus'requiring av sub-- stantial force in order to movethe damper blade. In order for the: damper to maintain a fairlyuni'eform draft it must be movable by a very small force. Thus when thebearings become rusty or dirty the damper remains stationary, eventhough the draft may change considerably.

The. primary object. of this invention is to provide a barometric orpressure operated damper which is not subject to loss of efficiency dueto age. This result is obtained by completely eliminating the usualbearing type pivots and mounting the damper blade on spring hinges whichflex to permit movement of the damper blade.

A further object of the invention. is to provide an arrangement forlimiting the curvature that the spring hinges may take, thereby insuringthat. the spring hinges operate well within their elastic limit.

Other objects of the invention will appear from the followingdescription and appended claims.

For a full disclosure of the invention reference is made to thefollowing detailed description and to the accompanying drawings, inwhich,

Fig. l is a front elevation of a barometric damper embodying theinvention;

Fig. 2 is a side sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is a bottom view of the damper:

Fig. 4 is a fragmentary side sectional view showing the damper in openposition;

Fig. 5 is a rear .view' on a reduced scale of thedamper frame; and

Fig. 6 is a view similar to Fig. 4 of a modified form of the invention.

Reference character i indicates generally a rectangular frame having arectangular opening 2Il spring hinges.

an inwardly extending portion 4' which is adapted for reception in athimble 5 which in turn may be mounted on the smoke pipe leading from afurnace. The frame I is also formed with a cross member 6 which extendsacross the opening 2 from one side of the frame to the other. As shown;in Figs. 2' and 4 this: cross memberis generally arcuate in shape. Thepurpose of this constructionwill appear as this description proceeds.

Attached to the front portion of the cross memher 5 are a pair ofupwardly extending normally fiat. spring hinges 8 and 9, one springhinge being located at one side of the frame and the other spring hingebeing located at the other side of the frame. Each spring hinge ispreferably clamped between the cross member 8 and a clamping member I 0,screws H serving to draw the clamping members Ill tightly up against theThe upper ends of the spring hinges are attached to the damper blade 3.This attachment preferably includes a clampingmember t2 for each springhinge and which is drawn up against its spring hinge by screws l3.

Attached to the lower central portion of the damper blade 3 is anoutwardly extending screw M; which carries an adjustable weight I5. Thisweight biases the damper in closing direction.

In operation, the diiference in pressure between atmospheric pressureacting on the right hand side of the damper, as seen in Fig. 2, andfurnace draft acting on the left hand side of the damper, tends to rockthe damper in a counter-clockwise direction. This action is opposed bythe weight I 5 which tends to rock the damper in a clockwise direction.When the furnace draft increases above the setting of the damper asdetermined by the adjustment of weight E5, the damper rockscounter-clockwise, thus permitting an increased amount of air to passdirectly into the flue and guide or limit the flexing of the springhinges.

This insures that the spring hinges will not buckle in service, andfurther insures that the fiber stress in the springs will not exceed theelastic limit.

It should be noted that the cross member 6 is slotted as at 18 and IT.These slots are provided in order to prevent the clamping members 52 forthe hinges from striking the cross member. Also the damper blade 3 isformed with depressions I8 and I9 which provide clearance for the springhinge clamping members Ill. The damper blade also may be formed withsuitable stiffening ridges such as 20.

It is desirable to provide suitable stops for preventing the damperblade from swinging outwardly from fully closed position. Such stops mayconsist of cars 22 and 23 which extend inwardly from the side members ofthe frame I. Preferably the damper blade 3 is formed with depressions 24adjacent these ears for receiving suitable cushioning pads 25 and 26which may be formed of felt. If desired, additional cushioning pads 28(Fig. 4) may be located in the depressions I8 and I9 of the damperblade. These cushions will insure that no metal-'to-metal contact takesplace between the spring hinge clamping members l and the damper blade,thereby insuring silence in operation.

In the embodiment of the invention illustrated in Figs. 1 to 4, thespring hinges flex solely about the arcuate portion of the cross member6. Fig. 6 illustrates a modified form of construction in which the crossmember 6a consists of a straight piece which extends from side to sideof the frame. Secured to the cross member fia is an arcuate cross memberEb which serves as a clamping member for the spring hinges. A similararcuate cross member 60 is attached to the damper blade 3 and serves toclamp the free ends of the spring hinges to the damper blade. It will benoted that the arcuate portions of members 61) and to cooperate to limitthe curvature of the spring hinges. If desired, a stop bracket 30 may besecured to the cross member 6a and extends through an opening 3| in thedamper blade. As shown, this stop bracket limits opening movement of thedamper blade. It will also be apparent that the stop bracket 30 preventsoutward movement of the damper blade from a vertical position, therebyproviding a stop for limiting closing movement of the damper.Preferably, two stop brackets 39 are provided, each bracket beingapproximately the width of the spring hinge, one bracket being locatedopposite one spring hinge and the other bracket being located oppositethe other spring hinge.

From the foregoing description it will be apparent that the presentinvention provides a new form of mounting of the damper blade in apressure actuated or barometric damper. It will further be seen thatthis new form of mounting completely eliminates the sliding contact asoccurs in the usual trunnion type pivots. This arrangement, bycompletely eliminating friction in the operation of the damper blade,insures that the damper will perform consistently over a long period oftime. In addition, this elimination of all friction makes the damperextremely sensitive to changes in draft and therefore permits the damperto hold the draft within closerlimits than the prior art devices.

While we have shown and described a preferred form of the invention, itwill be apparent that many changes in construction may be made withoutdeparting from the invention. We therefore desire to be limited only bythe scope of the appended claims.

What is claimed is:

1. In a damper, a support, a damper blade, a flat spring hinge havingone end secured to the support and its other end secured to the damperblade, an arcuate bracing member disposed adjacent the spring inposition to force a progressive pivot adjustment in the movement of thedamper, adjustable biasing means for biasing the damper blade towardclosed position, said spring hinge being arranged to cooperate with saidadjustable biasing means in biasing the damper blade toward closedposition.

2. In a pressure actuated damper, a frame having an opening, a damperblade for the opening, a cross member extending from side to side of theframe across said opening, and a pair of spring hinges, one at each endof the cross member, each spring hinge having one end attached to thecross member and its other end attached to the damper blade.

3. In a pressure actuated damper, a frame having an opening, a damperblade for the opening, a cross member extending from side to side of theframe across said opening, and a pair of spring hinges, one at each endof the cross member, each spring hinge having one end attached to thecross member and its other end attached to the damper blade, said crossmember having an arcuate section adjacent each spring hinge for limitingthe curvature thereof.

4. In a pressure actuated damper, a support, a damper blade, a pair offlat spring hinges for pivotally securing the damper blade to thesupport, means for limiting the curvature of said spring hinges, andarcuate means carried by the damper blade adjacent each spring hinge forlimiting the curvature of said spring hinges.

5. In a pressure actuated damper, a support, a damper blade, a flatspring hinge having one end secured to the support and its other endsecured to the damper blade, a first arcuate member carried by thesupport, a second arcuate member secured to the damper blade, saidarcuate members having constant radii of curvature and being disposedadjacent the spring hinge and limiting the curvature thereof so as toprevent stressing of the hinge beyond its elastic limit.

6. In a pressure actuated damper, a support, a damper blade, a flatspring hinge having one end secured to the support and its other endsecured to the damper blade, a first arcuate member carried by thesupport, a second arcuate member secured to the damper blade, saidarcuate members being disposed adjacent the spring hinge and limitingthe curvature thereof so as to prevent stressing of the hinge beyond itselastic limit, and a stop member adjacent said spring hinge, said stopmember being arranged to engage one part of the damper blade forlimiting movement thereof in one direction and to engage another part ofthe damper blade for limiting movement thereof in the oppositedirection.

7. In a pressure actuated damper, a support, a damper blade, a pair offlat spring hinges for pivotally securing the damper blade to thesupport, and arcuate means carried by the damper blade adjacent eachspring hinge for limiting the curvature of said spring hinges.

8. In a draft member an opening, a support adjacent said opening, a leafspring extending therefrom and secured thereto, a damper in operativeposition relative to said draft opening and secured to the spring, anarcuate member positioned adjacent the support and said spring wherebythe spring is constrained to conform to the arcuate member inprogressive hinge movement of the damper.

9. In a device of the character described a support and a leaf springsecured thereto and extending therefrom, a damper supported hingedly onsaid spring, and an arcuate member 5 disposed adjacent the spring inposition to receive pressure thereof in progressive hinge movement ofthe damper and said spring whereby the pivot point of said hingemovement progressively moves along the arcuate member.

10. In a device of the character described a support and a leaf springsecured thereto and extending therefrom, a damper supported hingedly onsaid spring, an arcuate member disposed adjacent the spring in positionto receive pressure thereof in progressive hinge movement of the damperand said spring whereby the pivot point of said hinge movementprogressively moves along the arcuate member, and a weight adjustablypositionable on the damper whereby to dif- 15 2,333,253

ferentially respond to the changing pivot point of said damper movement.

WAYLAND R. MILLER. HOMER E. MALONE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,959,222 Spear May 15, 19342,259,845 Valjean Oct. 21, 1941 Dady Nov. 6, 1945

